The manufacture of morpholines by heating diethanolamines or diisopropanolamines with excess sulfuric acid and then treating the mixture with alkalis has been disclosed. (U.S. Pat. No. 2,776,972) This process has the disadvantage that it produces by-product salts that are difficult to dispose of.
The cyclization of bis-(2-hydroxyalkyl)-amines by vapor phase dehydration over aluminum oxide and silicate catalysts at temperatures of from 300.degree.-400.degree. C. is disclosed in U.S. Pat. No. 2,597,260. This method produces large amounts of by-products.
A process for the production of morpholines is disclosed in U.S. Pat. No. 3,225,042, to Eli Lilly. In that process a methylenemorpholine is contacted with water, preferably in the form of a mixture with a water-miscible organic solvent.
In an article in J. Org. Chem. (1963), 28, 448, Dillard et al. discuss various methods of preparing substituted N-(2-hydroxyalkyl)propargylamines; and, their cyclization and subsequent hydrogenation to various morpholine derivatives is reported.
U.S. Pat. No. 4,068,077 discloses a process for the manufacture of morpholines by conversion of N-substituted bis-(2-hydroxyalkyl)amines. The cyclization of the N-substituted bis-(2-hydroxyalkyl)amines can be carried out in the presence of conventional catalysts containing aluminum, phosphorous, magnesium and calcium. In the second step suitable catalysts for hydrogenation are metals of Groups Ib, VIa and VIII of the Periodic Table.
These references do not appear to discuss the synthesis of new hydroxymorpholine compounds, nor do they discuss a novel process comprising reacting epoxides with primary amines in the presence of a ruthenium catalyst.
It would be an advance in the art to devise a process for producing hydroxymorpholines using mild conditions and a relatively inexpensive catalyst which did not produce large amounts of pollutants or unwanted by-products. In addition it would be desirable to devise a system whereby product distribution can be affected by varying reaction conditions or steric hindrance of amines.
These hydroxymorpholines could be useful as epoxy resin light stabilizing agents. Other hydroxymorpholines, represented by the formula ##STR2## have been reported to have the valuable pharmacological property of antimicrobial action.